Physical interaction of junctophilin and the Ca V 1.1 C terminus is crucial for skeletal muscle contraction

Significance For robust contraction of skeletal muscles, the L-type calcium channel acts as a key molecule by transducing membrane depolarization to calcium release from the sarcoplasmic reticulum. Proper intracellular localization of L-type calcium channels at the junctional membrane complex where the plasma membranes are closely apposed to the membranes of the sarcoplasmic reticulum is necessary for this process. Junctophilins are known to stabilize the structure of the junctional membrane complex by bridging the plasma membrane and the sarcoplasmic membrane. We report that junctophilins recruit L-type calcium channels to the junctional membrane through physical interaction with the Ca V 1.1 subunits of the channels. This protein–protein interaction at triads ensures efficient contraction in differentiated adult skeletal muscle.